Ceramic process



Sept 29, 1942- .1. R. THOMPSON 2,296,961' I CERAMIC PROCESS Filed oct. 2, 1940 JO-SEPH 7'0MPso/Y F Gttorneg ingbaseof'the Patented Sept. 29, 1942 UNITED Asfra'rlazs PATENT OFFICE onnnznzgicassji VJoseph n.1 Thompsonrt Liverpool, Ohio, as-

sl'snor to The Hall Gompany, East Liverpool, Ohio, a'corporation of Ohio Apparati@v october z', 1940,' serial No. 359,426'

' v 2Claims. (01.25-156) The present invention relates to an improved ceramic process or method of producing vitreous or semi-vitreous chinaware, especially, china- Figure 1` is a top plan view of a mold showing the necessary parts for a disclosure of my ware of the bowl type in which the bowl is fashioned with exterior` handles and a foot or hl'- low supporting base vbothjof which members are cast integral with the bowl. In carrying out the process of my invention I employ in one and the same mold, the step of casting the bowl with its integral handles from slip which is poured into a matrix formed between the base or core and the removable cope of the mold; and also the open-casting step of fas'hioning the integral foot or hollow supportbowl from slip a`s the mold is rotated.

As is well known in the ceramic art the slip employed is a homogeneous creamy wet mixture of finely divided clay and other ingredients. and the mold into which the slip is poured is made up of plaster of Paris or other porous and 4absorbent material which will absorb-the moisture from theslip 'or clay mixture. After the deposited material has set the separable cope-portion or upper portion of the mold is removed to permit the green bowl to season preparatory to sub.-

sequent steps in finishing, glazing, decorating, and otherwise completing the bowl for commercial purposes.

In carrying out my invention the bowl or other hollow vessel is fashionedfin inverted position, and the integral handles and hollow supporting base are united with and form part of the body of the bowl while the clay is in the best possible condition for such purpose.

The mold asawhole is dividedhorizontally,

and the cope or removable portion of the mold is divided vertically in order that the cope may be removed to uncover the green bowl, and an enclosing casing and other accessories (not herein shown) are or may be employed in mounting the mold upon a rotary head or ligger spindle for use as a vrotary former in the open-casting step in usualmanner. i

The invention consists in certain related steps in the manner of using the mold as will hereinafter be more fully set forth and claimed.

'In the accompanying drawing I have illustrated one complete example of a mold in which the steps of my improved process may be performed.

It will be understood however that changes and alterations may be made in the exemplifying drawing within the scope of my appended claims without departing from the principles of the invention. Y

understood that the process may be adapted for the production of other concavo-convex vessels or hollow-warehaving a hollow supporting base and exterior arms or ribs and lugs integral with the vessel.

In orderthat the steps of the process and structure of the mold may more readily be understood I have shown in Figure 3 abowl having the body B and a hollow supporting base in the nature of an annular flange F which is cast integral with the body B of the bowl. 'Ihe two exterior diametrically arranged handles H are also cast integral with the bowl. and these handles terminate in integral lugs L extending laterally of the bowl. Spaces indicated as S, S, are

provided between the handles and the bowl body, and dotted lines are employed to indicate the interior shape of the bowl and also the interior shape of the hollow supporting base-F of the bowl.

In Figure 1 where the outline of the bowl with its handles and end lugs are indicated by dotted lines, and in Figure 2 where the mold as a whole is shown as horizontally divided and the cope or upper removable section ofthe mold is shown as vertically divided, it is believed the disclosure is adequate for a clear understanding of the process of the invention. In Figure 2 it will be seen that the mold is supported upon a rectangular base l of-suitable material and preferably in one piece, and upon the upper face of the base is provided a circular recess 2 of suitable depth.

A centering ring or continuous rib l isl fashioned on the upper face 4 of the base I, and a domeshaped core 5 with tapering lower edge ismounted in the recess of the base. 'I'he upper or outer face 6 of the core is fashioned to desired shape so that the body of the bowl, in inverted position, may be built upon the core, and of course the interior of the bowl will conform to the shape of the outer face 6 of the core.

A central hole 1, that may be used for venting the interior of the hollow dome-shaped core, is closed with a tapered plug 8 while the molding or casting operations are progressing, and the dome-shaped core is fashioned with an exterior annular shoulder 8' above its tapered edge to assist in properly centering the core and in holding it in proper position.

It will be noted that the recessed base I, and the dome-shaped hollow core are each a unitary or one piece structure, and they form the drag portion of the mold. 'I'he cope or upper portion of the mold, however, is composed of two separable sections 9 and I0 that are vertically dividedand rest on the face 4 of the base member I' of the mold. These sections 9 and I0 are rigidly held together in suitable manner, as by the use of holes II and dowel pins I2 to provide a rigid structure, and this separable' cope member is clamped in suitable m/anner on the face 4 of the base so that when the clamp is released the cope may be removed by separating its two members 9 and I0. I

Each of the cope-sections 9 and I0 is fashioned with a semi-circular cavity and together these cavities forma circular face I3, or concave, that is spaced from the convex molding face 6 of the core to provide the matrix in which the slip is poured or deposited in the formation ofthe body B of the bowl.

Each of the sections 9 and` I0 is fashioned with half grooves I4 and |5 in the molding face I3 and each 'pair of half-grooves provides a radially extending groove that is instrumental in forming or molding a handle H on the exterior of the bowl. 'I'hese radially extending grooves terminate in lateral recesses I6 and II, also formed in halves in the abutting faces of the cope-sections 9 and I0, and these lateral recesses are instrumental in forming the free ends' of the handles or lugs L, L, of the handles.

The clay slip is introduced to the matrix preferably through two pouring passages I8, I8, each of which passages is formed by two complementary vertically extending recesses or groove/s in the abutting faces of the cope-section, and a suitable nozzle, or a funnel may be employed for discharging the slip into each passage. As indicated, the large passages 4terminate in forked sprue-holes I9 and 20, the sprue holes I9 opening into the matrix through the grooves I3 and I4, and the sprueholes 20 opening into the recesses I 6 and I'I, for proper distribution of the fluid clay. These pouring passages and ducts or holes are formed one-half in each of the abutting faces of the cope-sections 9 and I0, and abutting half-lugs 2|, 2| are also provided in these faces and located in the adjoining handle-grooves of the sections. These abutting half-lugs 2|, 2| form two cross bridges in the handle grooves, and these bridges are instrumental inthe formation of the spaces S, S, between the body B of the bowl and the handles H of the bowl.

In the top center of the removable and separable two-piece cope or upper mold-section is fashioned a mold cavity 22 which is shown with an annular groove 23 and a neck portion 24, the neck portion opening as shown into the main por, tion or matrix of the mold. This mold cavity with its annular' groove and neck is instrumental in the formation ofV the hollow supporting base F of the bowl, and the numeral 25 in Figure2 shows the dotted line formation of the hollow base.

As before stated, the body of the bowl or other hollow ceramic vessel, with its handles and lugs integral therewith, is fashioned within the matrix by pouring the fluid clay or slip through the passages I8, I8, and the sprue-holes I9 and 20, and it will be apparent that the lug-recesses I6 and |I and that portion of the matrix directly over the centering ring 3, first, are filled with the plastic material. As the matrix is gradually lled with the slip, air vented from the matrix through the central mold cavity 22, permits the formation of solid walls, handles, and lugs, of the inverted bowl. As the lowermost portion of the matrix becomes lled with the fluid clay, the body of the bowl is gradually built up, as are also the handles built up in their grooves I3 and I4, and the body- Wall of the bowl is imposed on the molding surface i of the core 5.

By pouring the slip at opposite sides of the center of the mold the fluent material is uniformly distributed throughout the matrix, and it will be apparent that by varying the width of the matrix between the two mold faces 6 and I3, the thickness of the walls of the bowl may be controlled as desired. In its inverted position, the body of the bowl is built up to a desired height by this step of casting the bowl on a core in the closed portion of the mold, and this desired height may be up to the junction of the neck 24 with the matrix, leaving open that portion which subsequently becomes the bottom of the bowl.

'Ihis unfinished bottom portion indicated by dotted lines 25 in Figure 2 and the hollow supporting base F of the bowl in Figure 3 are fashioned by the step of open casting during which the slip is poured into the open casting cavity 22 at the top center of 'the mold while the latter is revolving on a rotary head or :ligger-spindle in well known `manner. VAThis open casting step is performed immediately as a continuous operation in the method of manufacturing the bowl, the two steps utilizing the same supply of slip, and therefore the hollow foot or annular supporting base F is fashioned as an integral and intact portion ofthe bowl. Thepouring of the slip into the-casting cavity 22 is controlled so that the bottom 25 of the bowl and the flange F or hollow annular supporting base are built up to a desired thickness and as an integral portion of the bowl. As the slip is poured into the casting cavity 22, which forms a rotary former for the hollow supporting base, the material is thrown by centrifugal force into the annular groove 23 and against the annular surface of the neck 24 to form the hollow base integral with the bottom of the bowl. The wall of the supporting base follows the general outline of the casting cavity, the inside of the cavity of course `forming the outside of the supporting base.

The moisture from the slip, both with respect to the body of the bowl and the supporting base of the bowl, penetrates into the porous absorbent mold members, leaving the green body-wall of the bowl adhering to the core 5 and the supporting base-wall F adhering to the molding face of the casting cavity 22, and of course the escape or removal of the moisture from the cast piece due either to capillary attraction or to centrifugal action dries the cast article to a certain degree.

The green bowl is permitted to stand in its mold for a period of time suflicient for the plastic material to set and attain the proper condition to permit removal of the mold. The separable cope-sections 9 and 'I0 are .first removed from their enclosing positions exterior of the inverted bowl. The core 5, with the cast bowl mounted thereon may then be lifted from the base l and the green bowl is permitted to season for a sultable period of time before firing.

To facilitate handling of the core, it may be provided with diametrically arranged interior sockets 26,*26, into which the opposite ends of a stick or rod, (indicated as 21 by dotted lines in Figure 1) are inserted in order that after the mold has been `reversed from position of Figure 2 the core may be removed from the cast bowl.

As the slip dries it shrinks upon and adheres to the mold face 6 of the core, and, due to suction, or to atmospheric pressure, the' interior surface of the bowl remains in close contact with the molding face 6 of the core. To release these parts one from the other without marring the cast bowl, a gentle tapping on the smaller end of the tapered plug 8 breaks this close contact thereby permitting admission of air between the bowl and the core.

From the above disclosure it will be apparent that I have provided an improved method including a continuous succession of essential steps whereby a concavo-convex ceramic vessel with its exterior handles and its exterior hollow supporting base or foot may be cast in a single piece within a single mold and by a single operation of the mold. Inasmuch as the andles and foot are cast or molded integrally with the body of the bowl all appearance of a joint or unionbetween these parts is of course eliminated and the finish of the bowl-is enhanced as to its appearance. Thus the concavo-convex ceramic vessels such as casseroles, cups, sauce boats, sugar bowls,

creamers, 'and similar chinaware made according to my invention have a smooth exterior as well as a smooth interior surface. By my method of molding and casting, the production of ceramic articles having handles and feet or supporting bases of this type, is greatly enhanced, and the cost of production is reduced materially due to a more efficient use of time, labor, and material. The mold parts may readily be adjusted to vary the thickness of the walls of the vessel, and no surplus material is employed or renters into the structure of the vessel, only the designed quantity of slip being used to insure the desired form, shape, and size of the various integral parts.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent is:

1. The uninterrupted slip-casting method of forming an inverted bowl having integral exterior handles and an exterior integral hollow supporting base, which consists in forming the bowl and handles in the matrix of a closed stationary mold having an open central mold-cavity forming an upper extension of the matrix,

then rotating the mold and slip-casting the bowl- 

